Acquisition system for a multi-channel relatively long record length digital storage oscilloscope

ABSTRACT

A real time multi-channel digital storage oscilloscope acquires a relatively long data record for each channel in an acquisition memory and processes the data of the relatively long data record to search for predetermined events. Upon detection of such a predetermined event, circuitry generates an event detect signal, and data comprising an acquisition frame surrounding the event is applied to a waveform processing and display system. The relatively long data record can be replayed in order to perform additional searches throughout the data record using different search criteria, thereby permitting multiple waveforms to be displayed simultaneously, each being captured as a result of a different user-defined event. A screen display may be programmed to display a different kind of event such as Runt signal, Overshoot, or Pulsewidth Violation in each waveform, or to display multiple occurrences of the same kind of event such as Runt signal in each waveform. The multiple waveforms of the screen display may be derived from a single channel or from different channels.

FIELD OF THE INVENTION

The subject invention concerns, in general, the field of multi-channelDigital Storage Oscilloscopes (DSOs) having long record lengthcapability, and concerns in particular, an architecture for DSOs thatprovides improved digital signal processing of long record lengthwaveform data.

BACKGROUND OF THE INVENTION

The long-record-length features of modern long-record-lengthoscilloscopes are generally found to be very difficult and cumbersome tocontrol. Even when the available memory is apportioned to activechannels, the amount of data collected is difficult to use effectively(referred-to herein as a relatively long data record).

That is, when one has collected 8 Mbytes of data from four channels insuch a deep memory oscilloscope, how does one then use and interpretthat data? For example, assume a display of four rows of data (one foreach active channel), and further assume that the user wanted to scrollthrough the entire record looking for a particular event that caused aproblem in the system under test. For such a visual scan, ascrolling-rate of about 500 points per second is quite reasonable. Thatis, a particular point on each waveform would move across the screenfrom right to left in about 1.0 second. Unfortunately, at this rate itwould take approximately 4.375 hours for the user to view the entiredata record.

The fact that many oscilloscopes include a printer might lead one tothink that the solution to this problem would be to merely print out theentire record. For such a print out, a resolution of 300 points per inchis quite reasonable. Unfortunately, if the user were to print out such arelatively long record on paper in four rows at 300 points per inch(approximately 118 points per cm), the printer would use 0.421 miles(0.6736 km) of paper. These two examples highlight the difficulty indealing with large amounts of data. It simply is not practical for theuser to visually inspect all of the collected data for the anomaliesthat the user must find.

Modern DSOs attempt to solve this problem by waiting for a trigger eventto occur, and then acquiring in memory a frame of waveform datasurrounding the event. The frame is then processed by waveform mathsoftware, measurement software, and display system software. All of thispost-processing creates extremely long periods of “dead time”, in whichthe DSO is incapable of acquiring and storing additional waveformsamples. As a result, the anomaly that the user is searching for mayoccur, and be missed.

More recent DSOs have attempted to reduce the “dead time” by physicallypositioning Digital Signal Processing (DSP) ICs close to the acquisitionmemory to convert acquired waveform data to display data moreefficiently. This arrangement is sometimes referred to as a “FastAcq”mode of operation. Use of FastAcq circuitry has greatly reduced the“dead time” between triggers, and increased the number of samples persecond that are displayed. Unfortunately, the data frames processed bythe FastAcq circuitry are not retained, and are therefore unavailablefor additional processing. Moreover, cycle-to-cycle measurements (forjitter measurement) are adversely affected by the use of FastAcqcircuitry because the time relationship between successive triggers isnot maintained.

Another disadvantage of many current DSO architectures is a “bottleneck”that exists because they transfer all of the data from acquisitionmemory to main memory for processing and display over a relatively slow(i.e., typically 30 Mb/sec.) data bus.

In order to address this transfer-rate issue, Agilent Technologies, Inc.of Palo Alto, Calif., has recently introduced Infiniium MegaZoomdeep-memory oscilloscopes employing a custom ASIC that optimizes thesample rate for a given sweep speed and sends only the waveform dataneeded for a particular front panel setting. MegaZoom provides awaveform update rate that is approximately twenty-five times greaterthan conventional deep memory oscilloscopes.

Wavemaster™ oscilloscopes with X-Stream™ technology, manufactured byLeCroy Corporation of Chestnut Ridge, N.Y. provide an alternativesolution to the transfer-rate problem. These oscilloscopes employ asilicon-germanium (SiGe) digitizer and a high-speed streaming bus totransfer data from an analog to digital converter (ADC) through anacquisition memory and into a memory cache for extraction of informationby software routines.

However, what is needed is an oscilloscope having the capability torepeatedly “loop through” the four-channel relatively-long data recordin order to detect predetermined anomalies and produce a lively andactive display.

SUMMARY OF THE INVENTION

A real time multi-channel digital storage oscilloscope acquires arelatively long data record for each channel in an acquisition memoryand processes the data of the relatively long data record to search forpredetermined events. Upon detection of such a predetermined event,circuitry generates an event detect signal, and data comprising anacquisition frame surrounding the event is applied to a waveformprocessing and display system. The relatively long data record can bereplayed in order to perform additional searches throughout the datarecord using different search criteria, thereby permitting multiplewaveforms to be displayed simultaneously, each being captured as aresult of a different user-defined event. A screen display may beprogrammed to display a different kind of event such as Runt signal,Overshoot, or Pulsewidth Violation in each waveform, or to displaymultiple occurrences of the same kind of event such as Runt signal ineach waveform. The multiple waveforms of the screen display may bederived from a single channel or from different channels.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a simplified block diagram of the architecture for aconventional deep-memory digital storage oscilloscope, as known from theprior art.

FIG. 2 is simplified block diagram of the architecture of a MegaZoomdeep-memory digital storage oscilloscope, as known from the prior art.

FIG. 3 shows a simplified block diagram of an acquisition architectureemploying an FPGA for use in a digital storage oscilloscope, as knownfrom the prior art.

FIG. 4 shows a more detailed block diagram of the acquisitionarchitecture of FIG. 1, as known from the prior art.

FIG. 5 shows a block diagram of an acquisition architecture employing afirst arrangement of a processor and an acquisition memory for use in adigital storage oscilloscope in accordance with the subject invention.

FIG. 6 shows a block diagram of an acquisition architecture employing asecond arrangement of a System Processor and an acquisition memory foruse in a digital storage oscilloscope in accordance with a secondembodiment of the subject invention.

FIG. 7 shows a front panel arrangement of digital storage oscilloscopesuitable for use with the invention.

FIG. 8 is a simplified flowchart showing a Primary Acquisition and PostAcquisition Trigger Event Search routine, in accordance with the subjectinvention.

FIG. 9 is an illustration of a screen display in accordance with a firstaspect of the subject invention.

FIG. 10 is an illustration of a screen display in accordance with asecond aspect of the subject invention.

DETAILED DESCRIPTION OF THE DRAWING

The term “long data record” as used herein means a data record acquiredfrom a single channel and stored by concatenating all of the acquisitionmemory from all four data channels. The term “relatively long datarecord” as used herein means a data record acquired from at least twoactive channels and stored in memory allocated to the active channels.

FIG. 1 shows a highly simplified block diagram of a conventionalfour-channel deep-memory digital storage oscilloscope, as known from theprior art. Each channel has a respective analog-to-digital (A/D)converter 131, 132, 133, 134 for receiving an analog signal from acircuit under test via a probe and cable arrangement (not shown). A/Dconverters 131, 132, 133, 134, apply digital samples of their respectiveanalog signal to a Deep-Acquisition Memory arrangement 150. The term“Deep-Acquisition Memory” means a memory capable of storing data recordsof millions of points to billions of points in length. A CPU 170 thenprocesses all of the data of the data record for ultimate display on adisplay screen 180. There are two distinct problems associated with thistype of architecture. First, CPU 170 forms a “bottleneck” in that ittakes a significant amount of time to transfer such huge data records,resulting in dead time before another acquisition can be made. Second,CPU 170 may use an inordinate amount of computing resources to compress,for example, 32 Mpoints down to 500 points for display. Unfortunately,this expenditure of computing resources most often results in a viewablewaveform that is of very little use to the operator.

In FIGS. 1 through 5, similarly numbered elements have similar functionswhich need not be described again. FIG. 2 shows a simplified blockdiagram of the aforementioned Agilent Technologies Infiniiumoscilloscope with the MegaZoom feature. The MegaZoom feature employs acustom Application Specific Integrated Circuit (ASIC) 235 interposedbetween the A/D converters 231, 232, 233, 234 and The Deep AcquisitionMemory unit 250. ASIC 235 communicates with a front panel (not shown)and optimizes the sample rate for a given sweep speed and sends to theCPU 270 only that waveform data needed for a particular front panelcontrol setting. This operation significantly reduces the bottleneckdescribed above, and provides for the display of a more meaningfulsignal.

FIG. 3 shows a highly simplified block diagram of an architecture thatmay be similar to that used in the above-mentioned LeCroy WaveMaster™with X-Stream™ capability. This architecture is a significantimprovement over that of FIG. 1 in terms of its ability to transfer dataquickly from the acquisition system to the processing and displaysystem. These oscilloscopes employ a silicon-germanium (SiGe) digitizer355 which may be an FPGA and a high-speed streaming bus 390 to transferdata from an analog to digital converter (ADC) 331, 332, 333, 334through a Deep Acquisition Memory 350 and into a Memory Cache 370 forextraction of information by software routines.

FIG. 4 is a more detailed view of the architecture of the acquisitionsystem of a conventional deep memory oscilloscope. Referring to FIG. 4,Buffer amplifiers 401, 402, 403, 404, are associated with respectiveoscilloscope channels. Each of Buffer amplifiers 401, 402, 403, and 404amplifies analog signal applied to its input and applies the bufferedsignal to a Track & Hold unit 410 and to a Trigger ASIC 420. Track &Hold unit 410 is basically an analog switch used to route signals to theA/D Converters according to different interleave configurations. Track &Hold unit 410 also stabilizes the input signal and presents it to an A/DConverter 431, 432, 433, 434.

A Demultiplexer unit (DEMUX) 441, 442, 443, 444 is itself an ASIC thatreceives the digitized samples of the input signal from the A/DConverters 431, 432, 433, 434 and also receives trigger signals fromTrigger ASIC 420. As is well known, an A/D Converter produces datasamples at a rate that is faster than a memory can store them. To solvethis problem, a demux is used to reduce the rate at which memory-writeoperations occur by temporarily accumulating a series of high-speed datasamples from the A/D and then storing in memory perhaps 16 to 32 ofthese samples in a single memory-write operation. In this way, thememory is allowed sufficient time to store its data before beingpresented with the next group of newly acquired data samples. In theabsence of a trigger signal, the demux ASICs continuously write datainto memory. When a trigger signal is received, the demux ASICs continueto write data into memory for only as long as necessary to store therequired amount of post trigger data. At that time, data storage isstopped until a signal is received indicating that the acquisitionmemory has been unloaded into the processing system of the oscilloscope.Thus, DEMUX 441, 442, 443, 444 controls the flow of data into DeepAcquisition Memory 451, 452, 453, 454.

Unfortunately, none of the architectures illustrated in FIGS. 1 through4 allows a user to repeatedly “loop through” the long data record, whiletriggering on different criteria, and observe the result in a lively andactive display. An operator may realize that an anomaly is present inthe signal under test and that the anomaly is causing a problem.However, he may not know what the anomaly is. How does one set up atrigger if one does not know if the anomaly is taking the form of runt,or pulse width problem, or even a missing pulse? Thus, it is importantto be able to trigger on different criteria to detect the “unexpected”form of the variant, by changing the triggering criteria as onecontinuously loops through the long data record.

Such an oscilloscope architecture is shown in FIG. 5, and the subjectinvention will now be described with respect to FIGS. 5, 6, 7, and 8.Since FIGS. 4 and 5 are identical with the exception of the closephysical and logical association of a Processor unit (PROC.) 561, 562,563, 564, with a Deep Acquisition Memory 551, 552, 553, 554, previouslydescribed elements need not be described again.

In the apparatus of FIG. 5, any or all of the channels (i.e., CH 1through CH 4) are used to supply samples of the signal to be examined.In this regard, all of acquisition memories 551, 552, 553, and 554 maybe concatenated to form a single long record length memory, or allocatedto active channels. Processor unit (PROC.) 561, 562, 563, 564, may be amicrocomputer, but preferably is an FPGA (Field Programmable Gate Array)because an FPGA is capable of processing data up to 100× faster than amicrocomputer (i.e., up to 100× faster than an Intel Pentium IV™microcomputer). Deep Acquisition Memory 551, 552, 553, 554 has a datapath DATA1, DATA2, DATA3, DATA4, coupled to a bus leading to a SystemProcessor 570, that is, to its normal waveform data processing path.Note that Processor unit 561, 562, 563, 564 also has a data output pathlabelled, TIME STAMP, also coupled to the bus for providing time stampsdefining the frames of data to be processed and displayed. Processorunit 561, 562, 563, 564 also provides at least one trigger-type signalEVENT DET. (Event Detect). It is envisioned that EVENT DET. may in factbe multiple event detection signal lines coupled to System Processor570. Each trigger output is latched so that it can later be read todetermine which trigger event caused the post acquisition data frame tobe processed. Processor unit 561, 562, 563, 564 may be a singleprocessor controlling all acquisition memories, or a plurality ofprocessors wherein each processor is associated with a portion of theacquisition memory (as shown in FIG. 5). With the illustratedarrangement of processing units in all channels, both parallelsimultaneous triggering on predefined events is easily accomplished.Communication lines between the Processor unit 561, 562, 563, 564 arenot shown for simplicity.

FIG. 6 shows an embodiment of the invention in which the systemprocessor is programmed to also perform the function of post acquisitionexamination of the acquisition memory for the occurrence of specificpredetermined events. In the embodiment of FIG. 6, no separate processorunit is employed. Since FIGS. 5 and 6 are identical with the exceptionof the close logical association of a System Processor 670 with a DeepAcquisition Memory 651, 652, 653, 654, previously described elementsneed not be described again.

System Processor 670 may be a microcomputer such as, an Intel PentiumIV® microcomputer. Deep Acquisition Memory 651, 652, 653, 654 has a datapath DATA1, DATA2, DATA3, DATA4, coupled to a bus leading to SystemProcessor 670, that is, to its normal waveform data processing path.Because System Processor 670 is performing the event search itself,there is no need for generating an EVENT DET. (Event Detect) signal, aswas done in the embodiment of FIG. 5. With the illustrated arrangementof FIG. 6, System Processor 671 examines post-acquisition data acquiredin all channels and permits simultaneous display of all detectedpredefined events on a display screen of the oscilloscope.

FIG. 7 shows a front panel 700 for an oscilloscope having controlssuitable for use with the subject invention. The oscilloscope controlsare arranged in functional groups 710, 720, 730, 740, and 750.Functional groups 740 and 750 are arranged together in a furtherfunctional group 760. Front panel 700 includes standard control buttonssuch as CURSORS and AUTOSET and other control knobs that will not bedescribed in detail. Functional group 710 includes controls for menuselection, for selecting a channel, and for adjusting the scale andposition of the displayed signal waveform. Functional group 720 controlsthe timebase aspects of the signal to be acquired, such as Delay,Resolution, Record Length, and Sample Rate. Functional group 730controls the Display and includes controls for Horizontal Position,Vertical Position, Vertical Scale and Horizontal Scale.

Functional group 760 includes Functional groups 740 and 750, and also aset of controls for controlling how the oscilloscope is to acquire thewaveform samples of the signal under test. Specifically, a button isprovided for displaying an Acquire menu on the display screen of theoscilloscope. A second button, labeled MODE, selects among REGULAR MODE,DUAL MODE, and FastAcq MODE. An indicator located next to each of theselegends illuminates to show which mode is selected. The Illuminatedindicator is depicted in FIG. 7 by a crosshatched pattern. When anoperator wants to acquire a long length data record for Post AcquisitionSearch for Secondary Trigger Events, he selects DUAL MODE. In this modethe primary data acquisition record length is set to maximum, and thePost Acquisition Record length (Frame size) is set by the Record Lengthcontrol of Functional group 720. Functional Group 740 controls the PostAcquisition Event Search and includes a MENU button for displaying amenu including a list of trigger event criteria. Note that “replay” ofthe long length data record is controlled by pushbutton controls thatare similar in form and function to the controls of a VCR. In functionalgroup 740, indicators are illuminated to show that a Post AcquisitionEvent Search is active, and that the long record length data is beingplayed in a forward direction. Functional group 740 also includes aSCROLL knob for manually scrolling through a paused long record lengthwaveform from one event to the next. Functional group 750 containsstandard triggering controls and indicators.

FIG. 8 is a simplified flowchart showing a Primary Acquisition and PostAcquisition Trigger Event Search routine for a multi-channeloscilloscope. The routine is entered at location 800 and advances toblock 810 wherein the oscilloscope acquires a long record primaryacquisition using standard criteria for primary triggering. Afteracquiring the long record, the routine advances to step 820 whereinProcessor unit 561, 562, 563, 564 (preferably a high speed FPGA) of FIG.5 (or System Processor 670) searches the stored relatively long recorddata of each active channel in a Post Acquisition Event Search for ananomalous event. At step 830, a check is made to see if the event ofinterest was found. If not, the routine continues looking for it withinthe acquired relatively long record data. If so, then the routineadvances to step 840 wherein a frame of data surrounding the event issent to the waveform processing section of the oscilloscope, and anEVENT DETECT signal is generated. At step 850, the frame of PostProcessing anomalous event data is processed and the resulting waveformis displayed. A determination is made at step 860 of whether or not theend of the long record data has been reached. If not, the routine loopsback to step 820 and continues looking for events within the relativelylong record data. If so, the routine advances to step 870 to see if theoscilloscope is in One-Shot acquisition mode, or in Free-Run mode. If inOne-Shot acquisition mode, no new data should be acquired, so the YESpath is followed to step 820 and the search begins again within thepreviously acquired long record data. It in Free-Run mode (sometimescalled Autorun mode), a new long record length acquisition will beperformed, so the routine loops back to step 810 to acquire the newrecord before looking through it for Post Acquisition Events(anomalies).

There is a purpose for looping back to step 820 to continue searchingthrough the previously acquired long record data when the PostAcquisition Search Event was not found. By doing so, the routine createsa lively responsive display because the user can change the searchcriteria and immediately see a change on the display. For instance, theoperator may have set the Post Acquisition Search Event to be a Runtsignal event (i.e., a detection of a pulse whose amplitude did not reacha switching threshold before returning to its original state). Duringthe search the operator may change his mind and wish to search for apulse having an out-of-tolerance pulse width. Immediately upon adjustingthe search criteria, the displayed waveform will reflect the result ofthe new choice of event. That is, event types may be changed on-the-flyas the relatively long record length acquisition is being scanned.

FIG. 9 is an illustration of a screen display produced in accordancewith the subject invention. A display screen 900 of a digital storageoscilloscope is shown displaying eight waveforms 901, 902, 903, 904,901′, 902′, 903′, 904′. Waveforms 901, 902, 903, and 904 are displays ofwaveforms received via channel 1, and waveforms 901′, 902′, 903′ and904′ are displays of waveforms received via channel 2. Although fourwaveforms are shown for each channel, one skilled in the art willrecognize that any number of waveforms may be used. Similarly, althoughonly channels 1 and 2 are shown to be active, it is intended that any orall of the channels may be active and display waveforms simultaneouslyon-screen. Moreover, a screen display may include selected waveformsfrom each active channel.

Each waveform of FIG. 9 is exhibiting an anomaly that was detected andtime-stamped by apparatus according to the subject invention. A RecordBar 911 provides an indication of the relative length of the record, andthe positions of pointers 921 a, 921 b, 921 c, 921 d, 922 a, 922 b, 923a, 924 a, within Record Bar 911 are representative of the approximatelocations of the anomalies (i.e., Events) within the relatively longdata record.

As noted above, the relatively long data record is acquired by using thecriteria set in accordance with the normal trigger menu. Referring againto FIG. 9, an EVENT SOURCE menu 930 allows selection of the sourcewaveform that will be searched for anomalies. The menu choices areselected in sequence by repeated pressing of a pushbutton 935. In thiscase, the Acq Wfm choice is highlighted to indicate that an acquiredwaveform has been selected to be the source waveform. Other choices areeither of a Math Waveform (Math Wfm), or a reference waveform (Ref Wfm).Because Acq Wfm was selected, the next choice is that of the datachannel, in this case, Chan 1 and Chan 2 have been highlighted toindicate their selection. After the relatively long data record isacquired, the data is searched for anomalies in a post-processingoperation involving detection of the various anomalies and time-stampingtheir respective locations in memory.

Each of the four waveforms C1W1, C1W2, C1W3, C1W4 is controlled todisplay an anomaly (i.e., Event) chosen from a respective event menu951, 952, 953, 954, by repeatedly pressing an associated pushbutton 961,962, 963, 964. In this case, C1W1 displays examples of Runt signals,C1W2 displays examples of Pulsewidth violations, C1W3 displays examplesof Undershoot conditions, and C1W4 displays examples of Fall timeviolations. Processor 561, 562, 563, 564, or System Processor 670,extracted short record length waveforms 901, 902, 903, 904 from the longrecord length data stored in acquisition memory, in response to a searchfor preselected anomalies (i.e., Post acquisition Search Events).

Similarly, each of the four waveforms C2W1, C2W2, C2W3, C2W4 iscontrolled to display an anomaly (i.e., Event) chosen from itsrespective event menu 951, 952, 953, 954, by selecting a Channel 2waveform (e.g., by use of a touch screen) and then repeatedly pressingthe associated pushbutton 961, 962, 963, 964. In this case, forsimplicity of explanation, the anomalies chosen for the C2 waveforms arethe same as those chosen for the C1 waveforms. That is, C2W1 displaysexamples of Runt signals, C2W2 displays examples of Pulsewidthviolations, C2W3 displays examples of Undershoot conditions, and C2W4displays examples of Fall time violations; When a channel 2 waveform isselected, the Record Pointers change automatically to indicate thepositions of the anomalies within the channel 2 relatively long datarecord. It is intended that the memory depth of each record of allactive channels is identical.

Processor 561, 562, 563, 564, or System Processor 670, extracted shortrecord length waveforms 901, 902, 903, 904 from the relatively long datarecord stored in channel 1 acquisition memory, and extracted shortrecord length waveforms 901′, 902′, 903′, 904′ from the relatively longdata record stored in channel 2 acquisition memory in response to asearch for preselected anomalies (i.e., Post acquisition Search Events).

The legend displayed to the left of the waveform 901 indicates thesource C1 (channel 1), the selected kind of anomaly W1, and theoccurrence number of that kind of event in the long data record E1. Thatis waveform 901 is displaying the first occurrence 921 a of a runttrigger in the long data record. Similarly, waveforms 902, 903, 904 aredisplaying the first occurrence of their respective kind of anomaly 922a, 923 a, 924 a in the long data record, where pointer 921 b indicatesthe second occurrence of a Runt signal in the long data record, and soon.

Selecting a waveform (for example, by physically touching the waveformon a touch-sensitive screen) logically connects the SCROLL knob 975 tothat waveform. Thereafter, rotating the SCROLL knob 975 causes thewaveform to jump to a display of the next example of that kind of event,wherever it occurs in the long data record. For example, rotating SCROLLknob 975 will cause the runt signal associated with pointer 921 b to bedisplayed and to be labelled C1W1E2 (the second event of that kind).Selecting the second event will also cause pointer 921 b to behighlighted, and pointer 921 a to no longer be highlighted. SCROLL knob975 is the same control labelled SCROLL in functional group 740 of FIG.7.

Each of the waveforms is displayed with its anomaly centered on-screen(as shown by dotted vertical line 915) for ease of use. As noted aboveeach event is surrounded by data, the number of samples of which isdetermined by rotation of an EVENT RECORD LENGTH knob 985. Numericdisplay 980 indicates that 1.6 μs of time surrounds the event ofinterest, and each of waveforms 901, 902, 903, 904 includes the samenumber of samples surrounding the event of interest. Note that there isno time relationship between the displayed waveforms.

Because waveform 901 is associated with a particular kind of anomalywhose locations are indicated by pointers 921 a, 921 b, 921 c, 921 d, itis envisioned that the waveform and the pointers be displayed in thesame unique color (e.g., red). Similarly, waveform 902 is associatedwith pointers 922 a, 922 b and both should be displayed in a secondunique color (e.g., yellow). Waveform 903 is associated with pointer 923a and both should be displayed in a third unique color (e.g., green).Waveform 904 is associated with pointer 924 a and both should bedisplayed in a fourth unique color (e.g., blue). As noted above, theparticular pointer associated with the anomaly currently displayedon-screen will be highlighted to indicate its position in the long datarecord (see 921 a, 922 a, 923 a, 924 a). Other colors should be used inwaveform and pointer combinations from additional channels to avoidconfusion.

While the operation of apparatus of the invention with respect to FIG. 9is quite useful, one may wish to view all occurrences of single anomalywithin all of the relatively long data records. The screen display ofFIG. 10 provides an easy way to accomplish this goal. The majority ofthe elements of FIG. 10 are identical to similarly numbered elements ofFIG. 9, and need not be described again. Event selection menus 1051,1052, 1053, 1054 are used to program all of waveforms C1W1, C1W2, C1W3,C1W4, C2W1, C2W2, C2W3, C2W4 to display the same kind of event, a Runtsignal. All pointers in Record Bar 1011 have been removed except forthose 1021 a, 1021 b, 1021 c, 1021 d, 1021 e that indicate the relativepositions of runt signals in channel 1's relatively long data record,because a channel 1 signal (C1W1E1) is highlighted as being selected.Note that waveform W2 is labelled C1W2E2 to indicate that it isdisplaying the second runt trigger found, waveform W3 is labelled C1W3E3to indicate that it is displaying the third runt trigger found, butwaveform W4 is labelled C1W4E5 to indicate that it has been adjustedwith SCROLL KNOB 1075 to display the fifth runt trigger found. In thisregard, note that pointers 1021 a, 1021 b, 1021 c, and 1021 e arehighlighted, but 1021 d is not highlighted. The waveforms of channel 2are similarly numbered to indicate which event is being displayed.

Some examples of Post Acquisition Search Events (anomalies) are:

Jitter (width, rise, edge, etc.) Edge High Pulse width Low Pulseamplitude Min Rise time Max Fall time Max Telecom serial pattern RMSTelecom packet recognition Overshoot + − Wave Shape (matched filter)Histogram, stdev, mean, pk-pk Runt Eye Diagrams and mask triggersWaveform Comparisons Limits masks Peak-to-peak Frequency Period

One skilled in the art will appreciate that this list does not includeall possible trigger events, and the scope of the following claims isintended to be broad enough to include those trigger events notspecifically recited.

The term DUAL MODE has been used in describing the mode of operation ofthe subject invention. Use of this term is not critical to thepracticing of the subject invention, nor is this term is to beconsidered limiting in any way.

What has been described is a novel acquisition system for a long recordlength DSO that solves the “bottleneck” problem by only transferring thedata of interest to the main processing section of the oscilloscope.Also, the subject acquisition system maintains the data of the entirelong record in memory, thus preserving the timestamps of the data toallow post processing jitter analysis to be performed.

Throughout the specification the terms “event” and “anomaly” have beenused interchangeably to indicate a point of interest in the long datarecord.

While four Processing units 561, 562, 563, 564 have been shown, anddescribed above, other arrangements employing only a single processingunit may be used, and are considered to be within the scope of theinvention and covered by the following claims. The use of Processingunit in each channel permits simultaneous triggering on differentcriteria in each channel, thus permitting simultaneous display ofwaveforms relating to each trigger.

One skilled in the art will recognize that a given processing unit maybe programmed to recognize more than one kind of anomalous event.

While the four Processing units 561, 562, 563, 564 have been describedas preferably being FPGAs, one skilled in the art will understand thatuse of a microcomputer in this role will also work in an acceptablemanner, but the speed advantage of the FPGA will not be realized.Therefore the use of a microcomputer, ASIC, or other processor unit isconsidered to be within the scope of the invention and covered by thefollowing claims.

What is claimed is:
 1. An acquisition system for a multi-channel long record length digital oscilloscope, comprising: a plurality of input terminals for receiving signals under test; an analog-to-digital converter having an input coupled to said input terminals for receiving said signals under test, and producing digital samples of said signals under test at an output; a trigger circuit having an input coupled to said input terminals for receiving said signals under test, and producing a trigger signal at an output in response to detection of a predetermined trigger event in one of said signals under test; deep acquisition memory for storing said digital samples of said signals under test as a plurality of relatively long length data records that form a long length data record as a function of the trigger signal; and processor circuitry for examining said stored digital samples from the long length data record in a post acquisition mode of operation and producing an event detect signal in response to detection of a predetermined secondary event in said stored digital samples, and causing a predetermined amount of said stored digital samples to be read from said acquisition memory for processing and display; said predetermined amount of said stored digital samples being less than any one of the relatively long length data records and being related in time to said event detect signal.
 2. The acquisition system of claim 1 wherein: said processor operates in one of a one-shot mode and an Autorun mode; in said one-shot mode said processor circuitry repeatedly examines said long length data record; and in said Autorun mode upon completion of examination of said long length data record said processor circuitry causes the acquisition of new digital samples from said signals under test as the long length data record.
 3. The acquisition system of claim 2 wherein: data representative of said predetermined secondary event is input to said processor circuitry by a user for causing said processor circuitry to produce said event detect signal upon detection of said predetermined secondary event.
 4. The acquisition system of claim 3 wherein: said processor circuitry is responsive to input data entered by a user for changing said data representative of said predetermined secondary event; said input data entered by said user is accepted by said processor circuitry before or during said examination of said long length data record.
 5. The acquisition system of claim 4 wherein: said predetermined amount of stored digital samples represents a frame of samples surrounding said predetermined secondary event, and a magnitude of said frame is controllable by said user.
 6. The acquisition system of claim 5 wherein said oscilloscope has multiple channels: each of said channels having an acquisition memory associated therewith; each of said acquisition memories being concatenated with the others to form said deep acquisition memory.
 7. The acquisition system of claim 6 wherein said processor circuitry comprises individual processing units each of which is associated with a respective one of said acquisition memories of said channels.
 8. The acquisition system of claim 7 wherein: each of said individual processing units can be programmed to detect a plurality of different predetermined secondary events; and waveforms representative of data surrounding each of said different predetermined secondary events are simultaneously displayed on a display screen of said oscilloscope.
 9. The acquisition system of claim 6 wherein said processor circuitry is an FPGA.
 10. The acquisition system of claim 6 wherein said processor circuitry Is a microcomputer.
 11. The acquisition system of claim 6 wherein said processor circuitry is an ASIC.
 12. The acquisition system of claim 7 wherein said individual processing units are FPGAs.
 13. The acquisition system of claim 7 wherein said individual processing units are microcomputers.
 14. The acquisition system of claim 7 wherein said individual processing units are ASICs.
 15. A long record length digital oscilloscope, comprising: a plurality of input terminals for receiving signals under test; an analog-to-digital converter having an input coupled to said input terminals for receiving said signals under test, and producing digital samples of said signals under test at an output; a trigger circuit having an input coupled to said input terminals for receiving said signals under test, and producing a trigger signal at an output in response to detection of a predetermined trigger event in one of said signals under test; a deep acquisition memory for storing said digital samples of said signals under test as a plurality of relatively long length data records that form a long length data record; a demultiplexer unit coupled between said analog-to-digital converter and said deep acquisition memory for receiving said digital samples and controlling the flow of said samples to said deep acquisition memory in response to said trigger signal; processor circuitry for examining said stored digital samples from said long length data record in a post acquisition mode of operation and producing an event detect signal in response to detection of a predetermined secondary event in said long length data record; and a system processor for causing a predetermined amount of said stored digital samples to be read from said deep acquisition memory for processing and display in response to said event detect signal; said predetermined amount of said stored digital samples being less than one of the relatively long length data records and being related in time to said event detect signal.
 16. The long record length digital oscilloscope of claim 15 wherein: said system processor operates in one of a one-shot mode and an Autorun mode; in said one-shot mode said system processor repeatedly examines said long length data record; in said Autorun mode, upon completion of examination of said long length data record, said system processor causes the acquisition of new digital samples from said signals under test as said relatively long length data records.
 17. The long record length digital oscilloscope of claim 16 wherein: data representative of said predetermined secondary event is input to said system processor by a user for causing said system processor to produce said event detect signal upon detection of said predetermined secondary event.
 18. The long record length digital oscilloscope of claim 17 wherein: said system processor is responsive to input by a user for changing said data representative of said predetermined secondary event; said input by said user is accepted by said system processor before or during said examination of said long length data record.
 19. The long record length digital oscilloscope of claim 18 wherein: said predetermined amount of stored digital samples represents a frame of samples surrounding said predetermined secondary event, and a magnitude of said frame is controllable by said user.
 20. The long record length digital oscilloscope of claim 19 wherein: said system processor can be programmed to detect a plurality of different predetermined secondary events; and waveforms representative of data surrounding each of said different predetermined secondary events are simultaneously displayed on a display screen of said oscilloscope.
 21. The long record length digital oscilloscope of claim 20 wherein said system processor is an FPGA.
 22. The long record length digital oscilloscope of claim 20 wherein said system processor is a microcomputer.
 23. The long record length digital oscilloscope of claim 20 wherein said system processor is an ASIC.
 24. A digital storage oscilloscope, comprising: a plurality of input terminals for receiving signals under test; an analog-to-digital converter having an input coupled to said input terminals for receiving said signals under test, and producing digital samples of said signals under test at an output; a trigger circuit having an input coupled to said input terminals for receiving said signals under test, and producing a trigger signal at an output in response to detection of a predetermined trigger event in one of said signals under test; a deep acquisition memory for storing said digital samples of said signals under test as a plurality of relatively long data records that form a long length data record; a demultiplexer unit coupled between said analog-to-digital converter and said deep acquisition memory for receiving said digital samples and controlling the flow of said samples to said deep acquisition memory in response to said trigger signal; and a system processor for examining said stored digital samples from said long length data record in a post acquisition mode of operation for detecting a predetermined secondary event in said stored digital samples; said system processor causing a predetermined amount of said stored digital samples to be read from said deep acquisition memory for processing and display in response to said detection of said predetermined secondary event; said predetermined amount of said stored digital samples being less than one of said relatively long length data records and being related in time to said event detect signal.
 25. The digital storage oscilloscope of claim 24 wherein said oscilloscope has multiple channels: each of said channels having an acquisition memory associated therewith; said system processor being capable of being programmed to detect a plurality of predetermined secondary events in said acquisition memories; and waveforms representative of data surrounding each of said predetermined secondary events are simultaneously displayed on a display screen of said oscilloscope.
 26. The long record length digital oscilloscope of claim 25 wherein said system processor is an FPGA.
 27. The long record length digital oscilloscope of claim 25 wherein said system processor is a microcomputer.
 28. The long record length digital oscilloscope of claim 25 wherein said system processor is an ASIC.
 29. A method for use in an oscilloscope for displaying a waveform of interest comprising the steps of: acquiring data from a plurality of signals under test to form a plurality of relatively long length data records that form a long length data record in a deep acquisition memory in response to a trigger signal; examining the long length data record in a post processing mode of operation for the occurrence of a user-defined secondary event; upon detection of said user-defined secondary event, applying data comprising an acquisition frame surrounding the said user-defined secondary event to a waveform processing and display system.
 30. The method of claim 29 wherein: said relatively long length data records are replayed to perform said examining and said applying steps throughout the relatively long length data records using different predetermined search criteria defining different user-defined secondary events; and wherein said applying step causes multiple ones of said waveforms of interest to be displayed simultaneously, each being captured as a result of a different one of said user-defined secondary events.
 31. The method of claim 29 wherein said relatively long length data records are replayed to perform said examining and said applying steps throughout said relative long length data records using a single search criterion for said user-defined secondary event; and wherein said applying step causes multiple ones of said waveforms of interest to be displayed simultaneously, each being captured as a result of said user-defined secondary event. 